Sunbathing May Be Addictive

A new study on mice suggests that the body can become addicted to UV rays.

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TheGoodandtheBadofSummerSolstice:Photos

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Summer's here and the time is right ... for photos, to get us in the proper spirit for what's ahead. We'll take a look first at the good things augured by summer's arrival. Then, we'll remind you of the bad, just because we're realistic like that.
Our planet's Northern Hemisphere is ready for its metaphorical beachwear, as of June 21, which marks the summer solstice. Socially, the summer solstice means it's time for school to be out, for swimming, for barbecues. But astronomically speaking, it marks the longest day of the year. Of course, the poor Southern Hemisphere gets to start winter, but that's another story, and probably another gallery!
This image comes from NOAA's GOES-13 satellite and shows the Americas on June 21, 2012.
Sun Celebrates Solstice with Flare

NASA/Goddard Space Flight Center

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Life's a beach, right? What's more gooder than that? Time to break out the volleyball nets, accidentally crush children's sand castles, or just run in the water and then run back out again because it's still too cold for your liking.
Top 10 Beaches of 2013

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Don't have access to a beach? Go jump in a lake! OK, that came out wrong. Er, enjoy some fun in the body of water of your choice, if you can find one.
Lake That Turns Animals to Stone? Not Quite

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Hiking is the only way to climb, for some summer-timers. You might step out on the Tahoe Rim Trail, for example.
VIDEO: Monster Goldfish Invade Lake Tahoe

California State Parks

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For kids, summer means school's out and it's time for swimming. They'll spend as much time wet as dry.
Swimming Apes Take to the Pool

iStockphoto/Thinkstock

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Summer is also a time for barbecues. Your resident grill master will be rested and ready, after a winter spent staring forlornly at the giant Weber under the tarp.
12 Must-Haves for Great Grilling and Better BBQ'ing

iStockphoto

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If a BBQ's not your thing, maybe it's sailing. Of course, you might not have access to PlanetSolar’s catamaran Tûranor, the largest ship in the world to run on solar power alone, but you'll find a way to sail something in the water. An inflatable raft is always nice.
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And, now, we must turn to the bad ledger for summer. Bad as in worrisome, dangerous, or ... just a little bit annoying.
Remember the beach we saw earlier? Here's an unwelcome guest near any beach. Sadly, it will be a lucky summer if we don't hear many stories of sharks lingering too close to shore (and all of those big and small feet sloshing around in the surf). Sure, the shark can't help being a shark, but we'd rather he just stick to deeper waters.
Shark-Eat-Shark: Are Great White Sharks Cannibals?

Albert Kok, Wikimedia Commons

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Sizzzzzzle. We won't find anyone willing to put sunburns in summer's "good" column. Thankfully, there are plenty of sticks, creams, roll-ons and other assorted goop we can slather on ourselves to keep the sun's rays at bay. We all know the sunblock drill by now ... right?

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With the increased heat of summer, up also goes the likelihood of wildfires. We can all hope they're held at bay this summer, and that people are careful with their flammables out in the forest.
PHOTOS: Wildfire Season Off to a Hot Start

Just as likely as wildfires will be a heat wave or three. We're torn about this particular scene. No one likes a prolonged heat wave, but what's not fun about standing in a fountain? Perhaps this is a perfect place to end our gallery. Have a great summer, DNews readers!

ALY SONG/Corbis

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Do you find yourself constantly longing to soak up the sun? It might be about more than seeking that killer tan. A new study suggests sunbathing can actually become a kind of addiction.

As reported by New Scientist, David Fisher at Harvard Medical School and Massachusetts General Hospital in Boston showed that mice responded to UV light exposure with chemical response and behavior similar to those with drug addiction.

The finding could have significant implications since UV exposure is a known cause of skin cancer -- the leading kind of cancer in the United States. More than 3.5 million skin cancers in over two million people are diagnosed annually, according to the Skin Cancer Foundation.

For their study, Fisher and his colleagues gave mice a shave and then exposed them to UV light for five days a week. Each session was comparable to a fair-skinned person sitting in hot, Florida sun for 20-30 minutes.

After six months they noticed something peculiar. At the start of the study, the mice produced more feel-good hormones called beta-endorphins, which bind to opioid receptors – the same receptors at play with heroin addiction. Toward the end of the study, however, their levels of the beta-endorphins dropped (as evidenced by their decrease in pain tolerance).

Fisher said this suggests that the mice were building up a level of tolerance to the UV exposure. In other words to produce the same beta-endorphin-boosting effect, the mice required more time in the UV light. The scenario is similar to addicts who require more of their drug to achieve the same high.

The mice also displayed some classic signs of withdrawal behaviors including shaking, tremors and chattering teeth.

As Fisher told New Scientist, "We have a propensity towards seeking the most common carcinogen in the world."

Do we really all carry the potential to become sun addicts? The notion makes some evolutionary sense since our bodies require vitamin D and require some sun in order to synthesize the vitamin.

Some health experts, however, take exception to the comparison between overdoing it in the sun and becoming hooked on heroin.

"Even if an individual truly has no control over their compulsive behavior – even if they experience highs and lows, tolerance and withdrawal – that doesn't necessarily make someone an addict," cautioned Carlton Erickson, who works on addiction at the University of Texas at Austin.